In the operation of construction machines, it has been found desirable to steer the machine by rotating the front portion of the machine with respect to the rear portion. In order to do this, it is necessary to provide two separate frames that are pinned together about a vertical axis and extend hydraulic cylinders therebetween to obtain the desired rotation or articulation. Typically, the engine and drive train components are mounted on the rear portion of the machine and the work implement is mounted on the front portion of the machine.
In the case of some machines, the articulated wheel loader, for example, the front frame portion is subject to extremely high loads from several different sources. One primary source occurs during the steering function of the vehicle. Since the front axle is mounted to the front frame, there must be substantial support for it as it steered over all kinds of terrain. The forces applied by the steering cylinder to rotate the front frame with respect to the rear frame to steer the axle are also quite large. The support brackets for the steering cylinders are normally positioned on the sides of the front frame assembly at locations that are spaced from the axle centerline, through which the forces are transferred. As this spacing increases, so to do the forces passing therethrough, which ultimately requires exceptionally large support brackets for mounting structures.
These factors inherently result in a structure that is quite large in both height and width. With the increase in size however, come several disadvantages. The overall complexity and weight are exceptionally costly in terms of the numbers of components that must be welded together and the expense of material. Additionally, the operation of the machine is hampered because the large size of the structure can reduce the operators visibility to the work implement. This especially true with respect to the line of sight to the base and the corners of the implement.
The present invention is directed to overcoming one or more of the problems set forth above.